This invention relates generally to turbine engines and, more particularly, to methods and apparatus for assembling ceramic matrix composite (CMC) components.
At least some known turbine engines include at least one stator assembly and at least one rotor assembly that includes at least one row of circumferentially-spaced rotor blades. The blades extend radially outward from a platform to a tip. A plurality of static shrouds coupled to a stator block abut together to form flowpath casing that extends substantially circumferentially around the rotor blade assembly, such that a radial tip clearance is defined between each respective rotor blade tip and the flowpath casing. Ideally, minimizing the tip clearance facilitates improving turbine performance, but the clearance must still be sized large enough to facilitate rub-free engine operation through the range of available engine operating conditions.
During turbine operation, flow leakage across the rotor blade tips may adversely affect the performance and/or stability of the rotor assembly. However, during operation, because the shrouds may be subjected to higher operating temperatures than the stator block, the shrouds may thermally expand at a different rate than the stator block or the fastener assemblies used to couple the shrouds to the stator block. More specifically, such differential thermal expansion may undesirably cause increased tip leakage as the operating temperature within the engine is increased. Over time, the heat transfer from the shrouds and/or the differential thermal expansion may also cause premature failure of the fastener assemblies.
Accordingly, to facilitate reducing tip leakage caused by differential thermal expansion, at least some known engines channel cooling flow past the shrouds and fastener assemblies. However, excessive cooling flow may adversely affect engine performance. To facilitate increasing the operating temperature of the engine, and thus facilitate improving engine performance, other known stator assemblies use shrouds and fastener assemblies fabricated from stronger and/or higher temperature capability materials. However, as hot gas path temperatures increase, known mechanical fasteners may still prematurely fail.